(a) Field of the Invention
The present invention relates to a hybrid humidifier for a fuel cell, and more particularly to a hybrid humidifier for a fuel cell in which a plurality of humidifying tubes for supplying humid air discharged from a fuel cell stack are provided so as to uniformly humidify the inside of the humidifier, thereby improving humidifying efficiency.
(b) Description
A fuel cell vehicle is driven by driving force generated by a fuel cell which converts chemical energy generated by reaction of oxygen and hydrogen into electrical energy. For operation of the fuel cell, it is necessary to humidify electrolyte inside the fuel cell.
Generally, dry air out of a vehicle is supplied to fuel cell of the vehicle, and the dry air is humidified by a humidifier and then supplied to a fuel cell stack. The humidifier humidifies the dry air supplied from the outside using the hot and humid air that has been used in the reaction inside the fuel cell stack.
Although there are various humidifiers using a variety of humidification methods, such as supersonic humidification, steam humidification, evaporation type humidification, etc., humidifiers requiring smaller space and consuming less electric energy are preferred for a fuel cell. For this reason, humidifiers using an ultrafiltration membrane have been widely used for a fuel cell.
FIG. 1 is a cross sectional view of a conventional ultrafiltration humidifier, FIG. 2 is a perspective view of an ultrafiltration membrane module of FIG. 1, and FIG. 3 is a drawing showing air flow of the ultrafiltration membrane humidifier of FIG. 1.
As shown in FIG. 1 and FIG. 2, a conventional ultrafiltration membrane humidifier 1 has, at one side of the housing 10, a first inlet 20 through which dry air is supplied, and at the other side of the housing, a first outlet 30 through which the air humidified within the humidifier 1 is discharged. An ultrafiltration membrane module 60, which includes a plurality of module housings 62 containing an ultrafiltration membrane 64, is inserted into the housing 10.
The housing 10 also includes a second inlet 40 through which the hot and humid air discharged from a fuel cell stack is supplied. The housing 10 also includes a second outlet 50 through which the air humidifying the inside of the humidifier 1 is discharged. Moisture contained in the hot and humid air supplied through the second inlet 40 is separated by a capillary phenomenon of the ultrafiltration membrane 64, and then moves into the ultrafiltration membrane 64. The moved moistures serve to humidify the dry air passing through the ultrafiltration membrane 64 in a longitudinal direction thereof, and the humidified air is discharged through the first outlet 30 and is then supplied to a fuel cell stack.
However, as shown in FIG. 1 and FIG. 3, the dry air supplied from the outside is concentrated at a center portion A of the ultrafiltration membrane module 60 before being supplied to the humidifier, and the humid air spreads so slowly that it is difficult to permeate into the center portion of the ultrafiltration membrane module 60. Although an edge portion B of the humidifier 1 is humid, it has little air to be used for humidification, which deteriorates overall efficiency of the humidifier 1.
In addition, since water generated by the reaction in the fuel cell is supplied to the humidifier along with vapor, the water supplied to the humidifier may be frozen at a cold day so that efficiency may be deteriorated.
In order to recover the deteriorated efficiency, an attempt to use a number of ultrafiltration membranes has been made. However, this has a drawback that requires high manufacturing cost as well as increased size of humidifier.
There is thus a need for an improved hybrid humidifier for a fuel cell that can uniformly pass dry air to the humidifier to increase overall humidifying efficiency.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.